Electron tubes such as phototubes and photomultiplier tubes (PMT) have conventionally been known as photosensors. These electron tubes are constructed such that a photocathode which converts light into an electron and an anode are provided within a vacuum container. An example of such electron tubes is a photomultiplier tube in which a component having an inner face formed with a photocathode, a component formed with a photomultiplier part, and a component having an inner face formed with an anode are joined together (see the following Patent Document 1).
Meanwhile, as photosensors have recently been becoming versatile, the demand for reducing the size of electron tubes has been growing. On the other hand, a micropackage structure made by providing a silicon substrate and a glass sheet with respective bonding layers and joining the bonding layers to each other by a solder layer has been known as an example of microdevices having an optical function (see the following Patent Document 2).
Patent Document 1: U.S. Pat. No. 5,568,013
Patent Document 2: Japanese Patent Application Laid-Open No. 2003-175500